告别地球

2019 August 25

Leaving Earth
Video Credit: NASA/JHU Applied Physics Lab/Carnegie Inst. Washington

Explanation: What it would look like to leave planet Earth? Such an event was recorded visually in great detail by the MESSENGER spacecraft as it swung back past the Earth, eight years ago, on its way in toward the planet Mercury. Earth can be seen rotating in this time-lapse video, as it recedes into the distance. The sunlit half of Earth is so bright that background stars are not visible. The robotic MESSENGER spacecraft is now in orbit around Mercury and has recently concluded the first complete map of the surface. On occasion, MESSENGER has continued to peer back at its home world. MESSENGER is one of the few things created on the Earth that has left and will never return — at the end of its mission MESSENGER will be crashed into Mercury’s surface.

告别地球
像片提供: NASA/JHU Applied Physics Lab/Carnegie Inst. Washington

说明: 离开地球会看到什么景观？这种机会就出现在8年前，当信信使号水星探测飞船旋绕过地球前往内围的水星时，就曾传神且详细的记录了这种场景。在上面这部缩时影片中，可见到地球不停自转并逐渐远去。而受阳光照耀射的地球白昼面过于明亮，以至背景恒星都被淹没而不可见。在目前，信使号水星探测飞船位在绕行水星的轨道上，而且最近刚完成水星全部表面的照相工作。不过信使号偶然也会回首眺望它的家乡地球。信使号是少数建造于地球，在离开后永不复返的物体之一。因为在信使号任务结束时，它将会坠毁在水星表面。